Tire Casing Reinforcement with Low Permeability Metallic Cables
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Solution Overview
Problem
Heavy-duty tires face endurance issues due to 'fatigue-fretting-corrosion' phenomena, leading to reduced lifespan and increased manufacturing costs, particularly under severe conditions of load and temperature, and existing solutions with textile threads compromise endurance performance.
Innovation Solution
A tire design with a radial carcass reinforcement featuring metallic cables with a permeability rate of less than 20 cm³/min, integrated with textile yarns and an elastomeric mixture containing specific fillers and diene elastomers, providing enhanced cohesion and air drainage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cables with larger wire diameter are used for carcass reinforcement, then mechanical strength is improved, but flexibility and bending endurance deteriorate
Solution Approach 1:
The patent changes the wire diameter parameter to less than 0.28 mm (preferably less than 0.25 mm) to optimize the balance between mechanical strength and bending flexibility. This parameter modification allows the cable to maintain sufficient strength while significantly improving resistance to fatigue-fretting caused by repeated bending during tire rolling.
2Duration of action of moving object
If cable wires with small diameter are used to improve flexibility, then bending endurance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent creates a composite structure by combining multiple thin wires (diameter < 0.28 mm) into a cable assembly, where the collective arrangement provides the necessary mechanical strength while individual wire flexibility maintains bending endurance. The composite effect of multiple strands compensates for the reduced cross-sectional area of each individual wire.
3Productivity
If cable structure with channels is used, then air drainage is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent converts the harmful effect of air channels (which can conduct corrosive agents) into a beneficial feature by designing controlled channels that prioritize air drainage while minimizing corrosion pathways. The channel structure is optimized to drain air pockets efficiently during manufacturing while reducing exposure to oxygen and humidity that cause fatigue-corrosion.
4Reliability
If thicker rubber layer is used to reduce permeability, then corrosion resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent modifies the cable structure parameters (wire diameter, channel configuration, material composition) to achieve low permeability without requiring a thicker rubber layer. By optimizing the cable's intrinsic permeability properties through structural changes rather than increasing material thickness, the solution reduces manufacturing costs while maintaining corrosion resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tire exhibits improved endurance and manufacturing efficiency by limiting corrosion and fatigue effects, while maintaining attractive manufacturing costs, with the textile threads effectively draining air pockets and the elastomeric mixture enhancing cohesion under severe conditions.
Implementation Method 1
the textile threads effectively draining air pockets
Implementation Method 2
an elastomeric mixture containing specific fillers and diene elastomers, providing enhanced cohesion
Data Source
Figure 1a~2
Figure 1b
Figure 3~4
AI summary
The invention relates to a tire having a radial casing reinforcement consisting of at least one layer of metal reinforcement elements, said tire including a crown reinforcement, which is in turn radially covered by a tread that is joined to two beads via two sidewalls. According to the invention, the metal reinforcement elements of at least one layer of the casing reinforcement are cables having a flow rate of less than 20 cm3/min in the so-called permeability test, at least one layer of the casing reinforcement is provided on at least one surface consisting of fabric threads, and at least the elastomeric mixture layer, which is arranged radially outside the bead wire and which engages with the latter, consists of an elastomeric mixture containing natural or isoprene rubber and a reinforcing filler imparting high cohesion thereto.